Patent GB-1002417-A (GB)
Title: Transducer head system and method
Inventor: CAMRAS MARVIN
IPC: G11B9/00
Filed: 1962-02-21
Abstract: 1,002,417. Electric recording. I.T.T. RESEARCH INSTITUTE. Feb. 21, 1962, No. 6781/62. Addition to 896,691. Heading G5R. [Also in Division H1] To prevent troubles due to corona discharges on the sharp edges of the electrodes operating at the critical potentials required by the charge injection process described in the parent Specification, one or preferably both of the electrodes are shrouded by dielectric material where the recording face of the electrode(s) faces the incoming record material. The electrodes, such as used in the parent apparatus, may be so improved, but in particular, where one of the electrodes is a row of pins in a write/read cathode-ray tube, Fig. 1, the pins 40 are supported in a bulge 43 in the tube face which covers their sides, while the counterelectrode used in Fig. 1 is a pad of graphited felt 80. The elongate knife-edge electrode 180 of Fig. 7 is shrouded in epoxy resin 183. The recording modulation of a standing D.C. bias is applied to the electrode 80 in Fig. 1 and steady potentials are applied to the grid, cathode and internal coating 23 of the tube, whereas the modulation is applied to the coating 23 in Fig. 7. The grid may alternatively be modulated (Fig. 2, not shown). In Fig. 1, the pins 40 provide the recording definition transversely and longitudinally of a polyterephthalate record tape 43 while in Fig. 7, the electrode 180 provides the longitudinal definition, the pins 40 being switched by a conventionally deflected electron beam 20 completing the recording current circuit to each pin in turn. To reduce noise on the record, the pins 40 are set in a conducting glass face-plate of high resistance so that pins not connected by the beam 20 relapse to a uniform non-recording potential. The pins 40, for better engagement with the beam, may have their inner ends shaped, Fig. 5, and the beam 20 may be of elongate crosssection, Fig. 4. Where a television signal is being recorded, a sound-track is recorced longitudinally of a tapeedge by electrodes 80, 81, Fig. 1. To record conventionally interlaced vision signals, a tube with two rows of pins 231, 232, Fig. 9, has two counter-electrodes 245, 246 and the beam 233 is deflected to scan each row alternately, the lines of a complete frame 260, 266 being assembled in the same region 271 of the tape, the alternate blank frames 272 being used for a second recording. The tape may be developed xerographically and used as a cinematograph film by virtue of the sprockets 276. All the above tubes may be used for playback by including a load resistor to detect beam current variations when a recorded tape is fed past the pins 40 (Fig. 2, not shown) or tubes usable for playback only may be used. In Fig. 15, a pin potential repels the beam to a collector 345; in Fig. 16 the beam 360, curved by a transverse magnetic field is deflected relatively to electrodes 370, 371; while in Fig. 17, the width of the beam at 395 results from deflection at 392 and chopper plates 385, 386. Secondary emission dyondes may also be included. An electric vision recording may be made on a tape carrying a magnetic sound stripe (Fig. 22, not shown).